Self-advancing mine roof supports



Aug. 6, 1968 w. LUBOJATSKY 3,395,616

SELF-ADVANCING MINE ROOF SUPPORTS INVENTOR: v

WALTER LuoBrYArs/w ,q-ews. *Y

Aug- 6, 1968 w. LUBoJATsKY 3,395,616

SELF-ADVANCING MINE ROOF SUPPORTS Filed Dec. l2, 1966 5 Sheets-Sheet 2 716 21 17 73a P213 t WALTER LUBJ'ATS/(Y BY Q O Q fris INVENTORI Aug# 6,1968 w. LuBoJATsKY 3,395,616

SELF-ADVANCING MINE ROOF SUPPORTS Filed Dec. 12, 196e 5 sheets-Sheet sINVENTOR:

WALTER LU BOJATSKV 3,395,616 SELF-ADVANCNG MINE RGF SUPPORTS Waiter'Luhojatslry, Recklinghausen, Germany, assignor to Gullick Limited,Wigan, England, a British company Filed Dec. l2, 1966, Ser. No. 600,984Claims priority, application Germany, Dec. 22, 1965, B 85,095 Claims.(Cl. 91-412) This invention is for improvements in or relating toself-advancing mine roof supports of the kind in which the advance ofthe support is effected by a pressure-fluidoperated device hereinafterreferred to as a hydraulic ram.

In one known self-advancing mine roof support of this kind the advancingram has a cylinder secured to the support and a piston rod adapted to beattached to a coal face conveyor. After the passage of the mineralcutting machine the hydraulic ram is extended so as to push over theconveyor towards the newly exposed mineral face. The ram is thenretracted so that the support, after it has been temporarily releasedfrom between floor and roof, is advanced up to the conveyor. Thehydraulic leg or legs of the support are then extended to secure thesupport between floor and roof.

An alternative form of support of the self-advancing kind comprises twosupport elements connected together by an advancing7 ram. These supportelements are released from between floor and roof and advancedalternately, one support element, when secured between iioor and roof,serving as an abutment for the advance of the other support element.

It has been found advantageous, particularly in certain geologicalconditions, that the support should maintain some, although a lowpressure against the roof during its advance. For this purpose it hasalready been proposed to provide the hydraulic legs or props of thesupport with a bleed valve set so as to bleed-off sufficient pressure toallow the support to advance whilst at the same time maintaining therequired pressure against the roof. Such an arrangement has thedisadvantage that should the support meet an obstruction during itsadvance an excessive amount of pressure-fluid is discharged through thebleed valve and the support subsequently fails to maintain the requiredpressure against the roof.

It has also been proposed, whilst maintaining some pressure against theroof as the support is advanced, to discharge pressure-fluid from thehydraulic cylinders of the legs or props if there is an excessiveincrease in pressure on the pulling side of the hydraulic advancing ramsuch as will occur if the advancing movement of the support is impeded.Here again, there is a possibility of too much pressure-fluid beingdischarged with the result that the support fails to maintain therequired pressure against the roof during its advance.

It has also been proposed to maintain a pressure-fluid supply to thehydraulic cylinders of the props or legs during advance of the supportso that the roof-engaging structure of the support is held with therequired pressure against the roof. This arrangement has thedisadvantage that it requires a separate Huid-pressure source andfluidpressure main along the face to provide the particular pressurerequired in the hydraulic legs or props during advance of the support.

An object of the present invention is to provide a selfadvancing mineroof support capable of maintaining a required pressure against the roofduring its advance and notwithstanding that its advance may be impededtemporarily by irregularities in the roof or floor and which does notrequire a separate pressure source and pressureuid supply main along theface.

According to the present invention there is provided a self-advancingmine roof support comprising a base, hy-

3,395,616 Patented Aug. 6, 1968 draulically extensible leg means on saidbase, a roof-engaging structure mounted on said leg means and adapted tobe applied thereby to the roof, a hydraulic ram means operative toadvance the support and means for -connecting the leg means to thehydraulic circuit of the ram means so that the leg'means, during advanceof the support, is subjected to fluid-pressure, to maintain theroofengaging structure against the roof, dependent on the resistance toadvance of the support. Thus, when there is an increase in theresistance to advance of the support the pressure of the support againstthe roof is relieved and when there is a decrease in resistance toadvance the pressure is restored.

In one preferred arrangement the leg means, during advance of thesupport, is subjected to fluid-pressure, to maintain the roof-engagingstructure against the roof, dependent on the advancing speed of thesupport.

The advancing speed of the support depends on the resistance which thesupport encounters during its advance and pressure in the cylinder ofthe advancing ram is a measure of such resistance provided thecross-section of the pressure-fluid supply lines is proportionatelysmaller than the cross-section of the ram cylinder. The fluid-pressureto which the leg means is subjected during advance of the ram may,therefore, be controlled by means responsive to the pressure in thecylinder of the advancing ram. This is one preferred arrangement for thepurpose of the present invention.

Alternatively, the fluid-pressure to which the leg means is subjectedduring advance of the ram may be controlled by a force measuring devicebetween the advancing ram and one of its abutments, e.g. the fa-ceconveyor. For instance, if the connection between the piston rod of theadvancing ram and the conveyor includes a force measuring device, suchdevice will respond to the resistance to movement of the support and itsresponse can be used to adjust valve means controlling the supply ofpressure-fluid required to maintain the roof-engaging structure of thesupport against the roof during advance of the support.

In another preferred arrangement according to the invention thehydraulic leg means is supplied with pressurefluid from one side of adouble-acting advancing ram of the support whilst pressure-fluid isbeing supplied to the other side of said ram for the advancement of thesupport. Thus, the supply of pressure-fluid to the hydraulic leg meansis automatically dependent on the rate at which the support is beingadvanced by said hydraulic ram and the resistance which the advancingsupport encounters.

With the arrangement according to the present invention, if the supportduring its advance should meet with obstruction so that the rate ofadvance is reduced, there will automatically be a falling :off in thefluid-pressure supply to the hydraulic leg means. The latter will,therefore, be able to lower temporarily so as to clear the obstructionafter which, as the rate of advance of the support increases, thepressure-fluid to the leg means will increase so as to maintain theroof-engaging structure of the support in engagement with the roof withthe required degree of pressure.

The invention will be further described, by way of example, wit-hreference to the accompanying drawings in which:

FIGURE 1 is a side elevation of a self-advancing mine roof support ofthe kind to which the present invention may be applied,

FIGURE 2 is a diagrammatic representation of one embodiment of theinvention,

FIGURE 3 is a diagrammatic representation of a further embodiment, and

FIGURE 4 is a diagrammatic representation of a still further embodiment.

The support shown iu FIGURE l comprises a base having pivotally mountedon it in t-he usual way four hydraulically extensible telescopic legs 11arranged in pairs one behind the other.

Mounted on the upper parts of the legs 11 in the usual way is aroof-engaging structure or canopy 12.

Housed in and pivotally attached to the base 10 (eg. by means oflaterally projecting trunnions) is the cylinder 13 of a hydraulicadvancing ram for the support. The ram 13 has a piston rod 14 connectedby means of a vertically slotted clevis 15 to the face conveyor C.

It will be appreciated that a complete installation will comprise manyof the supports just described spaced apar-t along the face andconnected to the conveyor C.

After the passage of the coal cutting machine -along the face the ram13, 14 is extended so as to push over the conveyor C towards the newlyexposed face. The support is then advanced by retracting the ram 13, 14,pressure-fluid having rst been released from the legs 11 to an extentsuicient'to enable the support to slide between the floor and roof.During this advancing movement of the support suiicient pressure ismaintained in the legs to hold the roof-engaging structure with somepressure against the roof as hereinafter described in greater detail.

Referring now to FIGURE 2, 16 indicates a pressurefluid supply main forsupplying pressure-fluid to the hydraulic legs 11 and 17 indicates apressure-Huid supply ymain for supplying pressure-duid to the pushingside 13a of the ram 13.

It will be understood that the pressure-fluid supply main 16 and 17 mayserve the hydraulic legs and rams of the many supports spaced apartalong the face.

The supply of pressure-duid to the legs 11 and pushing side 13a of theram 13 is controlled by control valves 18 and 19 respectively. Thesevalves may also control the operation of other supports where aplurality of supports are operatedin groups or banks.

The valves 18 and 19 also have a position, for the purpose of thepresent invention, in which they connect the cylinders of the legs^11 tothe pushing side 13a of the ram 13 by way of a pipe 20. A non-returnvalve 21 is provided in the pipe 20 and said pipe 20 also has connectedto it a pipe 22 which discharges to atmosphere or is connected to areturn main. A regulating valve 23 is provided in the pipe 22.

Assuming that the conveyor C has been pushing over towards the newlyexposed coal face lby admitting pressure-fluid to the pushing side 13aof the ram 13, then, to advance the support pressure-duid .is suppliedt-o the re- 4tract side 13b of the ram 13 via a pressure-fluid supplypipe 24 and the valves 18 and 19 operated to a position in which theyconnect the legs 11 and the pushing side 13a of the ram 13 to the pipe20.

Thus, pressure-Huid can discharge from the legs 11 via the pipe 22 andregulating valve 23 so that the support is released from between floorand roof sufficiently to enable it to advance under the pull applied toit by retraction o-f the ram 13. During this advance, however,Huidpressure displaced from the pushing side 13a of the ram is madeavailable to the legs 11 so as to maintain the roofengaging structure 12against the roof.

If the ram advances without impediment fluid will be discharged from theram 13 to the legs 11 to such an extent that the roof-engaging structure12 will be applied to the roof with appreciable pressure although, ofcourse, not at a pressure which will materially impede the advance ofthe support. In other words, pressure-fluid from the ram 13 will, tosome extent, overcome the pressure iuid being discharged from the legsvia the regulating valve 23. On the other hand, should there be anobjectionable increase `in the pressure on the roof or should thesupport meet an obstruction such as the irregularity in the roofindicated at 2S, the advance of the support Will be retarded. As aconsequence, the rate of discharge of fluid from the pushing side 13a ofthe ram 13 will fall and there will be a corresponding fall in thepressure supplied to the legs 11. This will ease the pressure on theroof and the roof-engaging structure will be enabled to negotiate andmove under the obstruction 2S. Once it has done this the rate ofdischarge of iluid from the ram 13 to the legs 11 will increase andthere will be a corresponding increase of pressure on the roof. In otherwords, the rate of discharge of pressure-Huid from the ram to the legs11 will again become greater than the rate of discharge from the legsvia the valve 23.

It will be appreciated that the pressure applied to the roof duringadvance of the support can be pre-selected or controlled by anappropriate adjustment of the regulating valve 23.

The embodiment of the invention shown in FIGURE 3 is similar to thatalready described with reference to FIGURE 2 and where applicable likereference numerals have been used to designate like parts. In thearrangement shown in FIGURE 3, however, the regulating valve 23 isreplaced by a spring-loaded bleed or pressure relief or reducing valve26. When the roof-engaging structure 12 meets an obstruction 25 in theroof the valve 26, which is pre-set to operate at a required pressure,bleeds-oli pressure-fluid, to atmosphere or to a return line, andrelieves the pressure of the roof-engaging structure against the roof.Thus, said roof-engaging structure can negotiate the obstruction. Afterit has done this the bleed valve 26 will cease to bleed-01T fluid andsufiicient pressure will be restored to the legs 11 to maintain theroof-engaging structure in firm sliding contact with the roof. Even ifthe roofengaging structure should come under a cavity in the roof, suchas is indicated at 27, pressure on the roof will be maintained -becausefurther uid will be supplied to the legs 11 from the rarn via the pipe20. It will also be noted that in the arrangement shown in FIGURE 3 thenonreturn Valve 21 is omitted.

In the case of a walking support, i.e. a support comprising two supportelements which advance alternately each using the other as an abutment,the piston rod of the advancing ram may be connected to the one supportelement and the cylinder to the other. Such an arrangement is shown inFIGURE 4. The hydraulic system is similar to that described withreference to FIGURES l and 2 and like reference numerals have been usedwith the suflx a attached to those of the second support element 11a,12a. When the ram is being operated to advance the element 11, 12pressure-fluid is made available to the legs 11 from the side 13a of theram cylinder and when the ram is being operated to advance the element11a, 12a pressure-Huid is made available to the legs 11a from the side13b of the ram cylinder.

I claim:

1. A self-advancing mine roof support comprising a base, hydraulicallyextensible leg means on said base, a roof-engaging structure mounted onsaid leg means so as to be applied thereby to the roof, a hydraulic rammeans operative to advance the support and means for connecting the legmeans to the hydraulic circuit of the ram means so that the leg means,during advance of the support, is subjected to duid-pressure, ltomaintain the roof-engaging structure against the roof, dependent on theresistance to advance of the support.

2. A mine roof support -as claimed in claim 1 wherein during advance ofthe support said leg means is subjected to huid-pressure, to maintainthe roof-engaging structure against the roof, dependent on the advancingspeed of the support.

3. A mine roof support as claimed in claim 1 wherein the fluid-pressureto which the leg means is subjected during advance of the support iscontrolled by means responsive to the pressure in the cylinder of theadvancing ram.

4. A mine roof support as claimed in claim 1 wherein the ram means isdouble-acting and the cylinder of the ram means has a connection to theleg means of the support so that pressure-fluid discharged from the rammeans, during advance of the support, can act on said leg means to applythe roof-engaging structure to the roof, valve means being associatedwith said connection for controlling the ow of pressure-fluidtherethrough.

5. A mine roof support as claimed in claim 1 wherein said connectingmeans between the hydraulic circuit of the ram means and the leg meansof the support has an opening to atmosphere controlled by a regulativevalve.

6. A mine roof support as claimed in claim 1 wherein said connectingmeans between the hydraulic circuit of the ram means and the leg meansof the support has an opening to atmosphere controlled by a loaded bleedvalve.

7. A mine roof support as claimed in claim 1 wherein the ram meanscomprises a double-acting ram, a pushing side of the cylinder of saidram being connected to the leg means of the support.

8. A mine roof support as claimed in claim 1 wherein a cylinder of theram means has 4a connection to the leg means of the support so thatpressure-fluid discharged from said cylinder, during advance of thesupport, can act on said leg means to apply the roof-engaging structureto the roof, valves, for controlling operation of the support `and theram means, being positioned in said connection so as also to control theow of pressureuid between the ram means and the leg means during advanceof the support, a regulating valve having an outlet to atmosphere beingpositioned between said control valves.

9. A mine roof support as claimed in claim 1 wherein the duid-pressureto which the leg means is subjected during advance of the support iscontrolled by a forcemeasuring device between the support-advancing rammeans and Aan anchorage it uses to advance the support.

10. A mine roof support as claimed in claim 9 wherein saidforce-measuring device responds to resistance to movement of the supportand said response adjusts valve means controlling the supply ofpressure-Huid maintaining the roof-engaging structure of the supportagainst the roof during advance of the support.

No references cited.

EDGAR W. GEOGHEGAN, Primary Examiner.

1. A SELF-ADVANCING MINE ROOF SUPPORT COMPRISING A BASE, HYDRAULICALLYEXTENSIBLE LEG MEANS ON SAID BASE, A ROOF-ENGAGING STRUCTURE MOUNTED ONSAID LEG MEANS SO AS TO BE APPLIED THEREBY TO THE ROOF, A HYDRAULIC RAMMEANS OPERATIVE TO ADVANCE THE SUPPORT AND MEANS FOR CONNECTING THE LEGMEANS TO THE HYDRAULIC CIRCUIT OF THE RAM MEANS SO THAT THE LEG MEANS,DURING ADVANCE OF THE SUPPORT, IS SUBJECTED TO FLUID-PRESSURE, TOMAINTAIN THE ROOF-ENGAGING STRUCTURE AGAINST THE ROOF, DEPENDENT OM THERESISTANCE TO ADVANCE OF THE SUPPORT.